Method of manufacturing dehydrated zinc sulfid.



i To all whom it may concern CHARLES imnsoN, F 'PARIS, FRANCE METHOD orMANUFACTURING DEriYnRA'rEn-zmo siinrrnf M 1 1 71 ,246. No Drawing.

Be it known that I, CHARLES RANsoN,'of 2. Rue Poncelet, Paris, France,engineer, have invented a new and useful Improvement in the Method ofManufacturing Dehydrated Zinc Sulfid, which improvement is fully set'forthin the following specification.

Zinc sulfid obtained by the reactionof sol uble sulfids of the metals,of the alkalis or alkaline, earths upon solution of zinca tes of thealkalis or alkaline earths is a hydrated product which becomes anhydrousonly at temperatures exceeding 250 C. Atj this temperature, however itassumes a'yellow coloration which remains after -cooling.

,whereby its employment as a white paint is pre udicia1ly affected.Onthe other hand hydrated zinc sulfid oxidizes in the; air

somewhat readily and paints prepared with this product are deficient intheir'resistance to atmospheric influences in proportionto the amount ofwater the zinc sulfid contains, from which it follows that the zincsulfid must be dehydrated as much as possible if it is to besuccessfully used as palnt.

It has been found that the yellow coloration of sulfid of zinc: heatedabove 250 C.

a is due to the presence of a certain quantity of zinc oxid contained.in the zinc sulfid precipitated by the stated sulfids from solutions ofzincates of alkalis or alkaline earths, and

'- verting zinc oxid into zinc sulfid have'not that this zinc oxid ischemically vcombined with the zinc sulfid as it is insoluble in diluteacetic acid, while free zinc oxid readily dissolves therein. It has'alsobeen found that a product is obtained which can be completely dehydratedwithout becoming yellow on heating, if thechemically combined zinc oxidis converted into zinc sulfid.

The processes heretofore known for congiven a thoroughly satisfactoryresult in'the present case. Thus, for example, solutions of thestatedsulfids convert only a small part of the zinc oxid into zincsulfid, even after a lengthy boiling. 0n the other hand, the conversionis effected in the presence of a small excess 7 of ammonium sulfhydrateby heating undeupressure to; about 155 In the presence of a certainquantity of hydrofluoric acid the chemically comhined zinc oxid isconverted into zinc sulfid to such an extent that upon heating to'a redheat, the resultant product no longer becomes yellow. Finally, it isfound that the Specification of Letterslatent.

-1 atented-Feb. s, 191

" Application filed September 6,1910, Serial580,5 1i. J

' conversion can be effected by calcining the zinc-oxy-sulfid' with, acertain, quantity of; sulfur in the presencev of alkali or alkalineearth fl'uo-silicates which apparently act as facilitating agents. Thehydrofluoric acid can be replaced by hydrochloric acid, but the productso obtained becomes blackr in sun light unless it be subjected to afurther treatment which consistsin eliminating-the zinc chloridbyalkalis or alkaline earths.

The process can be carried into practice in the following manner: v 7

1. 100 kilos of] zinc oxy-sulfid' precipitatedifrom an alkalinesolution, filtered and washed are stirred in about liters of water, towhich a quantity of hydrochloric acidor'hydrofiuoric acid (halogenacids),'

corresponding approximately to 3 to 4 liters of concentrated acid, isadded. While agitating a current of sulfureted hydrogen is passedthrough until a drop of the mix- I fare on paper. impregnated with lea'dsalt leaves a black stain. The product isthen filteredywashed, 'driedand calcined at a temperature of from ,600 to 700 C. while excludingtheair. a

2. 100 kilos of' zinc oxy-snlfid as above are mixed with about 5 kilosof sulfur and- 1 to2 kilos ofsodium silico-fluorid or fluo-- silicate.This mixture is-calcined at atemperature of 600- 7 00 C. while excludingthe air. y

The resultant product is freed from fluorin compounds by washing n warmwater. If hydrochloric acid has been used,

an alkali or alkaline earth must be added to 4 the washing water forthe'purpose' of eliminating the whole of the chlorin which is presentfor themost part as zinc chlorid.

l. The process which comprises reacting upon a zincate with a solublesulfid to produce zinc oxysulfid as a' precipitate, and then subjectingsaid precipitate .in the presence of a flu'osilicate' to the action of asulfur containing'reagent capable. of replacing the oxygen of theoxysulfid by sulfur.

2. The process which comprises reacting upon a zincate with a solublesulfid -to.pro-, duce zinc oxysulfid as aprecipitate, then subjectingsaid' precipitate in the presence of a fluosilicate to the action of asulfur containing reagent capable of replacing the.

oxygen of the oxysulfid by sulfur, and then dehydrating, the product.

3. The process of preparing pigments i which comprises treating ,isulfi'd co -L Itaining Zinc-oxid with a sulfur-containing reagent in thepresence of a halogen compound capable of facilitatingtlie'sulfurization of the same by the sulfur-containing reagent! 4. Theprocess of 'preparing pigments vhich comprises treating zinc sulfidcontaining ZlIlC oxid with a;sulfur-containlng'reagent in the presenceof a compound containing a halogen.- acid'radical capable offacilitating'the sulfurization'of the same by the sulfur-containingreagent.

5. The process of preparing pigments which comprises treating zincoxy-sulfid with a reagent containing sulfur in avail .able form'ln'thepresence of a compound containing fiuorin and capable of facilitat-..ing'the sulfurization of the same by the sul 20 furcontaining reagent.

6. The process of preparing pigmentswhich comprises treating zincoxysulfid with a reagent containing sulfur in avail-' able form inpresence of a-fluosilicate, whereby the oxysulfid is converted into thesulfid.

'TfThe process of preparing pigments which comprises treating zincoxysulfi'd l-Gopies of this patent may be obtained for With a reagentcontaining sulfur in available form in the presence of sodiumfluosilicate, whereby the oxysulfidis converted into the sulfid. h

8; The process of preparing pigments which comprises heating a mixturecomprising zinc oxysulfid, sulfur, and an alkali fluosilicate, toconvert the oxysulfid into the sulfid i 9. The process of preparingpigments which comprises calcining a mixture comprising zinc oxysulfid,sulfur, and sodium fiuosilicate, under exclusion of air, to convert theoxysulfid into sulfid, and freeing the resultant product of fluorincompounds.

10. The process of preparing pigments which comprises treating zincsulfid containfive centseach, by'addressing the Commissioner of Patents,

Washington, D. 0,

